Add Desining Data-Intensive Applications book

and Martin's article on sharing topics for different events on kafka

README.md

@@ -108,6 +108,7 @@ At the moment this is not useful for anyone but myself, if at some point I find
         * [Coursera - Algorithms - Part 2 - Graph and string-processing algorithms](https://www.coursera.org/learn/algorithms-part2) 🆓 🎓 📼
         * [Courated List of the 10 best free resources](https://medium.freecodecamp.org/these-are-the-best-free-courses-to-learn-data-structures-and-algorithms-in-depth-4d52f0d6b35a) 📰 🆓
     * Databases
+      * [Designing Data-Intensive Applications - Martin Kleppmann](http://dataintensive.net) 💰 📕
       * SQL
         * PostgreSQL
           * [Updating a 50 terabyte PostgreSQL database](https://medium.com/adyen/updating-a-50-terabyte-postgresql-database-f64384b799e7) 📰 🆓
@@ -144,6 +145,7 @@ At the moment this is not useful for anyone but myself, if at some point I find
         * [Kafka](https://kafka.apache.org)
           * [Introduction to Kafka](https://www.youtube.com/watch?v=UEg40Te8pnE) 📼 🆓
           * [Commit Logs in an Age of Microservices - Tim Berglund](https://www.youtube.com/watch?v=bbotWkCLuF0) 📼 🆓
+          * [Should you put several event types in the same Kafka topic? - Martin Kleppmann](https://martin.kleppmann.com/2018/01/18/event-types-in-kafka-topic.html) 📰 🆓
           * Internals
             * [The Log: What every software engineer should know about real-time data's unifying abstraction](https://engineering.linkedin.com/distributed-systems/log-what-every-software-engineer-should-know-about-real-time-datas-unifying) 📰 🆓
             * [How Kafka's Storage Internals Work](https://thehoard.blog/how-kafkas-storage-internals-work-3a29b02e026) 📰 🆓